1. Field of the Invention
The present invention relates to a mobile terminal for making connections to a network such as the Internet using wireless, and particularly to a mobile terminal, such as mobile phone including automobile telephone or PTS (Private Telephone Service), for making access to various files.
2. Description of Related Art
A mobile terminal such as mobile phone, PTS has widely been used by virtue of its ease as well as a computer for making connections to a network through wire, and recently, the practice of making access to the Internet to receive information on a home page or exchange electronic mail has been performed ordinarily.
With regard to accounting as a network usage charge of the case of using such a mobile terminal to use a network, any one of two methods has been adopted conventionally. One method is to settle the accounting according to the amount of data when data is sent and received through the network. For example, in packet communication, when predetermined information about a dissertation etc. consisting of text information is read by one page, data is sent and received as a packet every page turning, but in the case other than the reading, no load is imposed on a network. Hence, in such a case, it is rational to settle the accounting according to the amount of data sent and received. The other method is to settle the accounting according to time during connection to a network. This method has widely been used in accounting for telephone etc. conventionally, and offers the advantage in the case that the amount of data sent and received every unit time is large.
An administrator of each the network attempts to settle the accounting based on any one of the methods by a contract with a user or by oneself. Thus, the user can conduct economical communications by selecting the network according to a form of the use.
In a technique described in JP H10-190845 A, it is constructed so as to prepare a table for controlling a communication charge etc. per unit time under the circumstances that a mobile terminal is connected to a server through several kinds of mobile communication networks. Then, it is constructed so that the minimum communication time or the minimum communication charge is estimated using this table before starting communication and according to this estimation, a user can determine the optimum mobile communication network to start the communication.
Also, in a technique of JP H11-313074 A, it is constructed so that at the time when data communication is started between a client machine and a server machine and sending of unit data is completed, based on information about a throughput of the case of using another server machine, processing time necessary for the case of switching a line to this server machine to conduct data communication from the beginning is calculated. Then, it is constructed so as to reduce the communication time by again conducting communication by the latter server machine if it is determined that more efficient communication can be conducted to again conduct data communication from the beginning using the server machine other than the server machine by which the communication has been conducted presently.
However, these two techniques assume that information sent and received is one kind. Therefore, it cannot cope well with the case that the information sent and received is formed of several files with respectively different characteristics. For example, when access is made to contents (home page) on a server, various files or data such as text information described by HTML (Hypertext Markup Language), JPEG (Joint Photographic Experts Group), MPEG (Moving Picture Experts Group), etc. are present in the contents. When an attempt is made to receive mail, various files or data may be attached to the mail similarly. In a technique of JP H11-113061 A, an idea of speedily conducting data communication in which plural data are mixed is performed.
FIG. 9 shows a technique for sending and receiving plural data disclosed in this publication. First, a communication channel with a communication destination is established to become a data communication state (step S101). In this state, a kind of data of the first target of communication present in the head of data storage means for storing data to be sent is detected by data kind detection means (step S102). Then, a protocol corresponding to the data is selected by protocol selection means (step S103) and data communication about the data is conducted using the protocol (step S104). Thereafter, it is checked whether unsent data is present in the storage means or not (step S105) and if so (Y), the communication destination is notified of switching of the protocol (step S106), and the kind of the next data is detected (step S102) and data communication is conducted by a protocol corresponding to this (steps S103, S104). The similar operations are performed below.
Also, in a technique of JP H11-32378 A, a proposition to improve the point that an information channel TCH of two channels provided between a mobile phone and a base station has conventionally been used in only voice communication or only data communication is made. In this proposition, it is constructed so as to measure the amount of transfer data when a need to conduct data communication during voice communication arises. Then, after always ensuring an information channel TCH of one channel for voice communication, it is constructed so as to select the proper channel for data communication from low-speed accompanying channels or high-speed accompanying channels based on the amount of data measured.
However, in the technique described in JP H11-113061 A shown in FIG. 9, a kind of communication data is determined in a state in which communication networks are established and according to the kind, a protocol with the communication destination is switched. Thus, while there is a merit that data communication is conducted more efficiently by the switching of the protocol, a method of data transfer is selected only within a range of the established communication networks and efficient communication cannot be conducted in case that the selected communication networks are inadequate. Therefore, there was a problem that even when efficient communication was conducted within the connected communication networks, there is a possibility that a communication charge becomes lower if other communication networks are used.
Also in the technique described in JP H11-32378 A, this point is similar. Further, in this technique, it is constructed so as to always ensure the information channel TCH of one channel for voice communication. Therefore, for example, even if the voice communication is unnecessary, one channel is ensured for voice communication so as to receive electronic mail to which a file is attached, so that there was a problem that one channel becomes a free channel entirely and efficient use of the connected communication networks cannot be made.